Method of making a photoelectrolytic imaging device

ABSTRACT

In the manufacture of a photoelectrolytic imaging device, an aqueous suspension is formed of all the ingredients making up the image forming layer. The aqueous suspension is then spread evenly over an electrically conductive support for the image forming layer and a photoconductive layer then placed in contact with the aqueous suspension layer.

United States Patent Inventor Harvey A. Hodes Eatontown, NJ. App]. No. 874,388 Filed Nov. 5, 1969 Patented Dec. 14, 1971 Assignee The United States of America as represented by the Secretary of the Navy METHOD OF MAKING A PHOTOELECTROLYTIC IMAGING DEVICE 1 Claim, No Drawings u.s.c1 .1 117/230,

117/201, 1 17 34, 96/1 E 1m.c1 G03g5/l0 Field ofSearch 117/201,

215,230, 34; 96/1 PC, I E, l LY, I R

[56] References Cited UNITED STATES PATENTS 3,393,337 7/1968 Paneraietal. ll7/215 Primary Examiner-William L. Jarvis AnorneysHarry M. Saragovitz, Edward J. Kelly. Herbert Berl and Roy E. Gordon METHOD OF MAKING A PHOTOELECTROLYTIC IMAGING DEVICE The invention described herein may be manufactured, used, and licensed by or for the Government for governmental puroses without the payment to me of any royalty thereon.

This invention relates to an improved method of making a photoelectrolytic imaging device. The improved method can be used in the manufacture of photoelectrolytic imaging devices as disclosed and claimed in the US patent applications of Hodes and Zerner for Photoelectric Imaging Device, Ser. Nos. 670,815 and 670,816 filed Sept. 26, 1967 and now abandoned and assigned to the same assignee.

BACKGROUND OF THE INVENTION Photoelectrolytic imaging devices have been fabricated from two parts. One part is an image forming monomer layer on an electrically conductive support. The other part is a photoconductive layer on an electrically conductive glass support such as Nesa glass. Before exposure, the two parts are brought together to form an integrated device, and a negative or some image pattern placed or focused on top of the glass.

The image forming layer referred to above is made up of polymerizable or image forming ingredients dispersed in a suitable binder, such as gelatin or agar. This composition or emulsion is then coated onto a suitable substrate such as stainless steel. Then, a small amount of an aqueous liquid containing an electrolyte is applied to the surface of the emulsion and the photoconductive layer then pressed on top of the image recording layer making sure that there is a liquid contact over the entire surface of the emulsion-photoconductor. This liquid junction is needed for good electrical contact. A disadvantage encountered with the above set forth technique is that the gelatin or agar or other type binder-emulsion does not contain over ten percent solids. These solids are made up of the polymerizable monomers plus electrolytes plus initiators. If more than about ten percent solids is incorporated in the emulsion, the solids precipitate out when the emulsion sets, as a coating. Another disadvantage is the necessity of a binder such as agar or gelatin being present which, due to its physical bulk density, interferes with the polymerization reaction.

SUMMARY OF THE INVENTION The general object of this invention is to provide a method of making an improved photoelectrolytic imaging device. A particular object of this invention is to provide such a method wherein the available concentration of monomer in the image forming layer of the device can be substantially increased.

A still further object of the invention is to provide such a method wherein no binder such as gelatin or agar is required in image forming layer of the device so that both speed and resolution can be improved.

The improved method of this invention is attained by depositing the image forming monomer layer on the electrically conductive support in a particular manner prior to placing the photoconductive layer in contact with the image forming layer, The technique involves first forming an aqueous suspension of all of the ingredients making up the image forming layer including image forming monomer, electrolyte, viscosity thickener, buffering agent, and reducing agent. The aqueous suspension is then spread evenly over the electrically conductive support for the image forming layer. Then, the

photoconductive layer is placed in contact with the aqueous suspension layer.

DESCRIPTION OF THE PREFERRED EMBODIMENT A suspension is prepared as follows: milliliters of water is rapidly stirred while adding 2 grams of methocel. On complete solution, there is added the following: 0.5 grams of potassium chloride, 30 grams of acrylamide, 2.0 grams of N 'N methylenebisacrylamide, and 5.0 grams of trimethylenebisacrylamide. The pH is adjusted to 4.5 to 5.0 using ethyl mercapto acetic acid; then 0. l 5 gram of diphenylcarbazide is added The composition is spread evenly over the conducting metallic substrate; the photoconductive layer IS placed over it, and exposure is made in the usual fashion. In the alternative, the composition is placed in a pod, which prior to exposure is ruptured, and spread evenly as before, and exposed as before. To prevent overflow of the viscous composition, usual practice is to pour the composition into a preformed mold on the substrate. The mold thickness is not critical, but is of the order of 8 to 15 mils. Other thickening agent may be used, as for example, polyvinyl alcohol, 20 percent; sodium carboxymethyl cellulose, 4 percent; polyvinyl pyrrolidone, 20 percent; agar, 5 percent; acacia, 15 percent; gelatin, 15 percent; all percentages by weight of total composition.

In the method as above described, the concentration of monomer in the image forming layer has been increased about five times and the amount of liquid has been increased from 10 percent to about 98 percent. This is important as in polymer chemistry, it is well known that the speed and degree of polymerization is directly proportional to the concentration of monomer. Not so obvious, but equally important, is the fact that polymerization proceeds more rapidly in a liquid rather than a semisolid medium. The technique of this invention, which increases both the concentration of monomer and the amount of the liquid medium, results in a marked improvement in the imaging system. That is, the photographic processing time required to obtain a visible image on the electrically conductive support has been reduced by about 50 percent.

We wish it to be understood that we do not desire to be limited to the exact details of construction described, for obvious modifications will occur to a person skilled in the art.

What is claimed is:

1. In the manufacture of a photoelectrolytic image device wherein an image forming monomer layer is deposited on an electrically conductive support prior to placing a photoconductive layer in contact with the image forming, the improvement including the steps of:

A. forming an aqueous suspension by adding 0.5 grams of potassium chloride, 30 grams of acrylamide, 2.0 grams of N'N methylenebisacrylamide, and 5.0 grams of trimethylenebisacrylamide, to a solution of 2 grams methocel in I00 milliliters of water; adjusting the pH to 4.5 to 5.0 with ethyl mercapto acetic acid; and adding 0.15 gram of diphenylcarbazide;

b. spreading the aqueous suspension evenly over the electrically conductive support for the image forming layer; and

c. placing a photoconductive layer in contact with said aqueous suspension layer.

I! I i 1! 32 33 UTTTTED STATES TATENT OFFICE QETIFIQATE 0F QQEQTEGN Patent No. $627,578 Dated l4 Decenber 1971 InventorO/j HARVEY A. HODES It is certified that error appears in the above-idehtified patent and that said Letters Patent are hereby corrected as shown below:

r fi ange the Assignee from "Secretary of the Navy" to Secretary of the Signed and sealed this 13th day of June 1972.

(SEAL) Attest:

EDWARD M,FLEI'CHER, JR. ROBERT GOTTSCHALK Attestlng Officer Commissioner of Patents 

